Erza proved herself to be a good mother to Natsu and Gray. She nursed them and kept them warm. When they got older she taught them how to hunt, track, and fight. How to speak the language of the animals and follow the law of the jungle but most importantly she taught them how to adapt. Despite being born human the boys learned to adapt animal like qualities.
Natsu had developed the strength and senses of the dragon while Gray developed the speed and agility of the tiger. They were also very resourceful and creative. Like once Gray made a spear to help him get fruit when he couldn't climb far enough to reach it and another time Natsu made a cup like object that allowed him to draw water from the river when it was too crowded for him to find a place to drink from. They didn't wear clothes but they felt the need to hide their lower bodies so occasionally when a storm would blow stray pieces of clothing from the village of Alvarez or the Fiore settlement they would take them and use them to their advantage.
Natsu once caught a stray old brown vest caught in a tree. He folded it and made it into a loincloth. Gray found some black pants floating down the river. Using his spear he cut them to make shorts. Erza would also wear bits of stray human clothing to cover her female parts but only when she was in her more anthropomorphic form.
Both boys were incredible fighters though they weren't nearly as good as their adopted mother and they were rather rambunctious and mischievous boys. Always getting into fights and causing trouble whenever Erza's back was turned but like most good mothers she was always one step ahead of her boys.
For example this morning Erza had just come back from a swim and was in the middle of grooming herself. Natsu and Gray now ten years of age were hiding in the shadows and preparing to sneak up on her and give her a jump scare. Natsu crept up from the bushes while Gray slid down from the tree trunk. They were mere centimeters away from Erza when she said...
"Don't even think about it you two."
"How did you know it was us?" Natsu asked.
"I'm your mother I know everything. Now don't you boys have anything better to do then try to upset me?"
"We could always fight." Natsu said looking at Gray and cracking his knuckles.
"No. You two are brothers that means you're family And what do I say about fighting with family?"
"Your family is your ally not your enemy so it's wrong to fight them." Both of them said.
"That's right. Now run along, play, hunt, do whatever but no fighting and please stay out of trouble."
"Yes Mom."
The boys ran off the edge of the river where banna trees grew. While Natsu would sit up in the trees and try to eat as much bananas as he could, Gray would spend hours swimming in the cool river.
"Why don't you come in for a swim Natsu?" Gray asked. "The water's great."
"You know I can't swim Gray."
"You could if you weren't scared of the water."
"I'm not scared of the water. I just don't like water."
"You're scared and you know it."
"Am not!"
"Are to!"
"Am not!"
"Are to!"
"Am not!"
"Are to!"
"Well at least I'm not scared of the red flower like you are."
"Hey my fear is rational. Every animal is afraid of the red flower. Every animal except Jellal because he can make it."
"Well he won't be the only one for long. Someday I'm going to make the red flower."
"You idiot only dragons can make it."
"How do you know I'm not a dragon?"
"You're not a dragon."
"How do you know? You don't know what I am."
"You're right I don't know what you are, heck I don't even know what I am but I'm positive that we're not dragons."
"Why do you think that we're not dragons?"
"You've seen Jellal right?"
"Right."
"Okay then you know that we look nothing like him. He has scales, fangs, and talons. We don't."
"Then maybe we're tigers like Mom."
"Well we have fur like she does but it's only on our heads and we don't have claws or a tail. Come to think of it how come Mom has never told us what we were?"
"How should I know? It's not like she ever said anything to me. Oh wait I think I have a good idea on what we are."
"What?"
"Well monkeys have paws and feet like we do right?"
"Yeah."
"So maybe we're monkeys."
"You know what I think?"
"What?"
"You're a moron."
"Hey!"
"I am not a monkey! I do not eat bugs that I find in my fur and I don't throw poop! Ugh!"
"You like to climb trees like them."
"So does Mom but she's not a monkey. Here's an idea why don't we just ask Mom what we are when we get home?"
"Okay, okay, so what do we do until then?"
Suddenly they heard the proud, trumpeting calls of the elephants and felt the ground shaking motion caused by their footsteps as they marched through the jungle. The boys looked at each other and grinned mischievously.
"Time to scare the elephants." They both said.
Another thing that they liked to do was frighten the elephants because they were rather neurotic and sometimes senile creatures. Erza had told Natsu and Gray many times to leave them be but something about an elephant's proud and pompous nature seemed to just annoy them to the point of where they couldn't help themselves.
The elephants divided into different groups. One group went to the right to much on tree leaves and grass while the second went to the left to get water at the river. Natsu chose to scare the group of elephants on the right. He hid in one of the bushes then at just the right moment he released a mouse that he had caught earlier that morning.
"Mouse!" One elephant squealed in terror.
"Run for your life!" Another bellowed.
Soon they were all in a running frenzy. Natsu burst out laughing and rolling around on the floor.
Gray had gone after the ones on the left. As they were drinking from the river Gray hid himself in a tree and made a cry that sounded exactly like the growl of a predator.
"Tiger!" One elephant cried.
"Bear!" Another shouted.
"Wolf!" A third screamed.
Gray laughed so hard that he almost fell out of the tree. He then climbed down to meet Natsu.
"How did it go?" He asked his salmon haired brother.
"Better than planned."
"Sweet and since Mom is out hunting in the West part of the jungle she didn't see us."
"She didn't see you but I did."
The two boys froze with fear when they heard the chilling voice of their mother's mate Jellal. They turned around to find the blue dragon glaring at them. He changed into his anthropomorphic form, grabbed them by their waists, and carried them under his arms back to the den where he dropped them at Erza's feet. She could tell by the enraged spark in her mate's eyes that her boys had caused trouble.
"Oh no. What did they do this time?" She asked.
"What do you think? They were frightening the elephants again!" Jellal told her.
"Natsu, Gray what have I told you two about doing that?"
"We were just joking around." Natsu said.
"Do you have any idea how dangerous it is to frighten a heard of elephants?! You could have started a stampede and gotten someone killed!" He shouted at them. "But do you care?!"
"Jellal that's enough. I will handle it." Erza said.
"No! Of course you don't! Because you're selfish and you only care about your own wants and needs! Not anyone else's! You don't care about who you hurt!"
"Jellal I forbid you to speak to them that way!"
"What they did was dangerous!"
"Yes and I will reprimand them for it I promise you! But they're children! They don't mean any harm! They just don't understand! But they'll learn!"
"It's been ten years and they're still causing trouble!"
"You need to calm down."
"Don't tell me to calm down! Every time I see those two they're always doing something dangerous! If you didn't care so much for them I swear I'd-"
"Jellal that temper of yours is going to get you into a lot of trouble someday!"
"Temper?! Erza you haven't seen my temper yet! And as for them! When are you going to realize that they'll never be any good to us?! That it's in the nature of creatures like them to just take and destroy!"
"One more word Jellal and I swear I'll scratch your face off! Get out of here and don't come back until you calm down!"
She growled at her mate, he growled back but she stood her ground so he ended up leaving and going somewhere to cool off. Once he was gone she looked back to see Natsu and Gray huddled up together in a corner, absolutely terrified.
"Are you scared?" She asked. They nodded. "Good now you know how those poor elephants you frightened feel."
After that day Natsu and Gray never bothered the elephants again but they were confused and curious about what Jellal had said.
"Mom." Gray said. "What did Jellal mean when he said that it was in the nature of creatures like us to take and destroy."
"Don't pay any attention to him especially when he gets angry like that. He doesn't know what he's talking about." Erza told them.
"Why does he hate us Mom?" Natsu asked.
"It's not really you two that he hates."
"Then who does he hate?"
"He hates the ones who stole his wings."
"Who are they?" Gray asked.
"It's complicated. I'll tell you someday, for now let's just eat."